Then the more Internet users, the higher the response time icmp command ping.

What did:
1. At the beginning of the renewed the old to the new version Kerio Control, upgrade the rules http, filtering off.
2. Disable sophos, snort, web filter, cleaned all cashes and http, and dns.
3. Install again - the result is the same.

Please help, what could be the problem. Because downgrade to the previous version - everything works fine.

Is it repeating pattern for whole day, or specific time of day?
What %'s in CPU load? How many users connected?
Try this.
Make a rule, that blocks all traffic from your clients, except only your test pc, then check "ping 192.168.1.7 -t" (i.e. scenario 'kerio server<->single user')

Btw, do you have "block IP of password guessing attacks" option enabled?

The protocol inspector was the last culprit and resort to try to disable. I didn't told yet, cause most would just refuse to drop it. But seems like you found yourself.
Additionally, you can try this.
Divide your traffic rules, so that you have only ports HTTP and HTTPS with protocol inspector enabled (try 'http' instead of just 'default'). And clone the rule, with all other ports like, SMPT etc. to be below the first, and set inspector to 'none'.
See if that helps, and report back.
One guy on this forum also noticed that inspector on mail port doesn't work as expected.

EDIT: disable protocol inspector on every rule, leaving only those that use 80,443 ports.
Also, no need to inspect traffic on deny rules.

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